Pediatrics is defined as the branch of medical science which is concerned with the health of infants, children and adolescents, their growth and development, and their opportunity to achieve full potential as adults.

i) Definitions of Age Group Terminology:

1.Gestational Age–

Gestational age is defined as the number of weeks from the first day of last menstrual period (LMP) of the mother until the birth of the baby.

2.Postnatal Age-

It is the chronological age since birth of the baby.

3.Postconceptional Age–

Age since conception. Postconceptional age is calculated as gestational age plus postnatal age (Postconceptional age = Gestational age + Postnatal age).

4.Neonate–

A full-term newborn of 0-4 weeks postnatal age. It also means a premature neonate whose postconceptional age is 42-46 weeks.

5.Premature neonate-

Neonate born at <38 weeks gestational age.

6.Full-term neonate-

Neonate born at 38-42 weeks (average 40 weeks) gestational age.

7.Infant–

1 month (>4 weeks) to 1 year of age.

8.Child/Children–

1-12 years of age.

9.Adolescent-

13-18 years of age.

10.Adult–

>18 years of age.

ii) Different useful Formula

•  Formula for Body Surface Area
• Formula for determination of Weight & Height from Age
• Formula for Detection of Intravenous Infusion Time & Flow Rate.